221 



prove, by an affection of a distant seat, that the latter ever acknow- 

 ledged, with respect to the former, a dependence as for properties 

 habitually, or even occasionally received in the condition of health. 

 Hence, the facts which have been quoted to prove either the inherent 

 muscular power of the heart, or the remote dependence of this 

 power, are alike inadequate. I say nothing about the idle experi- 

 ments made on the heart by galvanism, electricity, &c. which are 

 scarcely worthy to form an amusement for a school-boy. Those 

 also who have sought for analogical proofs from frogs, toads, 

 and fishes, had very little more wit than the subjects of tlvir ex- 

 periments. The multiplication of useless facts, and of those which 

 are irrelevant to important conclusions, tend rather to impede, than 

 to promote the progress of science. 



6. There are then no facts which prove whether all the pro* 

 perties of the heart are assimilated in this seat, or whether some of 

 them are derived from another, and superadded to the assimilating 

 ones. The voice of analogy must here also be silent. We have 

 ascertained a certain dependence of the voluntary muscles on the 

 nervous centres; but we cannot transfer this fact to the heart. We 

 are told that some secretions, as the gastric, &c. are suspended by a 

 division of the eighth pair of nerves; yet we know that other secre- 

 tions, as those of lymph, pus, &c. will proceed in the arm, which is 

 paralyzed, or in the leg of an animal after a division of the axillary 

 plexus. In short, we cannot decide the point by a just reasoning on 

 the facts we possess; and therefore, as with all other doubtful mat- 

 ters, it is best to acknowledge it undecided. 



7. 2. The relations of blood in the cavities of the heart may 

 be considered, 1st, with respect to the vital properties of the organ*; 

 2nd, with respect to its material structure. 



8. That the motions of the heart are not dependent upon the 

 quality of the blood contained in its cavities appears to be proved 

 by the fact, that either ventricle will contract upon venous or 

 arterial blood. And that the motions of the ventricles are not de- 

 pendent upon the volume of blood, or produced by a repeated dis- 

 tention, appears to be deducible from the fact that the movements 

 of contraction and dilatation continue when the circulation has 

 ceased. Hence, the blood in the ventricles appears to contribute 

 nothing essential to the function of the heart. A strict and minute 

 inquiry may perhaps indicate that the movements of the heart are 

 liable to be affected by varieties in the volume of blood in its 

 cavities: this, indeed, we may pretty reasonably infer from analogy. 

 But the fact, if admitted as one, is very short of proving an habitual 

 dependence of the action of the heart, upon a fluid which is poured 

 into it, rather to suffer, than to act. 



9. If the blood in the cavities of the heart is not necessary to 

 the function of this organ, what are we to say of its relation with its 

 assimilating life? Does the blood in the ventricles maintain this 

 organic spirit, or is it assimilated from the vessels which ramify in 

 its structure] We observe that the functional properties never sur- 



